Your camera will typically have trouble focusing in any really dark scene. So here are some tips for dealing with that situation and focusing your camera when it is dark:
It is assumed that you should know to use a sturdy tripod.
1. Aim for the brightest spot
Even though it is dark, most night scenes will have a bright spot or two. They might be streetlights, or a lit-up building, or even the moon. That bright spot can be used to set your focus.
To do so, find a bright spot that is reasonably close to your desired plane of focus (i.e., the same distance away as your focal point). Focusing on that point should take care of your problem. Just focus on that bright spot in a normal fashion and your camera is now focused on something the same distance away as your subject. You should then be able to take your picture with proper focus.
2. Turn off Image Stabilization or Vibration Reduction
Most lenses now come standard with image stabilization (Canon) or Vibration Reduction (Nikon). If you’re using this while the camera is on a tripod and there is nothing that could cause the camera to move around, this setting can actually work AGAINST you and make your photos just out of focus. I learned this the hard way. I couldn’t figure out for the life of me why the image was blurry until I remembered that someone told me to turn off IS on my lens. Bam. Tack sharp!
3. Use a flashlight if need be
If you are attempting to focus on a relatively close subject, you can use a flashlight to assist with the focus. This is one of the many reasons to keep a flashlight in your camera bag.
To do that, shine your flashlight on your subject. That will lighten it up enough for the camera to focus on it. Set your focus, then you can turn off the flashlight and take your shot. (or, light paint an interesting foreground with it)
4. Recompose after focusing
Assume you now have your focus set using the methods set forth above. But to get that focus, you had to move your camera away from your desired composition to focus on the edge of a bright spot. Move your camera back to your desired composition to get the shot. Don’t refocus as you do so though – just move the camera and take the shot with the focus you’ve already set. (You will need to either hold the shutter button part way down, use focus lock, or focus and then turn off the AF so it doesn’t attempt to refocus once you have recomposed – or see #5 below.)
5. Use back-button focus
Seriously. Just do it! It is times like this, when you want to take a shot with out refocusing, that back-button focus really pays dividends. If your camera allows it, go into the menu and set up your focus so that it is not triggered when you press the shutter button halfway down, but rather is triggered when you press a button on the back of your camera. That way with your focus not set to the shutter button, when you take the picture by pressing it there is no chance that your camera refocuses. None. Nilch. Nadda.
6. Manually focus to the “Infinity” setting
This is a well known trick that photographers use all the time. Set your focal length between the bracket and the infinity symbol in your lens and take a test shot. Fine tune focusing by slightly adjusting to the left or right. On one of my lenses, I have to go just slightly left of the bracket for the sharpest result.
7. Set Mirror Lock-up
Most of the time with night photography you’re going to be using a longer than normal shutter speed. The less movement that occurs within and surrounding your camera will yield the best results for sharp photos. Set your mirror-lock up setting if you have a DSLR. If you have a mirror-less camera you do not need to worry about this.
I have used with great success mirror-lock up with a two second timer shutter release. This way there is no camera movement by me pressing the shutter release button. You could also use a wireless remote or a wired remote as well. Use what you’ve got. Think outside the box!
8. Use Live View
If you can see anything on your camera’s LCD using Live View, then you can use that to manually focus. This is frequently better because you can zoom in on your subject and clearly see if you have nailed the focus. Try using this whenever possible, as it allows a degree of control over focus that is not otherwise possible.
9. Remember you have unlimited film!
One of the beautiful things about digital photography is that shooting is free. Unless your scene is moving in front of you, you get a free do-over. Use it liberally. Take a shot, look at it on the LCD, and if the focus isn’t right, just do it again. If your camera allows it, go ahead and zoom in on the preview to clearly see the detail and whether or not you have nailed the focus.
These tips will help you set your focus at night or when you are in a dark scene. In fact, some of these tips will also help in broad daylight when the camera thinks it is dark because you are using a 10-stop neutral density filter. Try them when your focus is hunting but not finding anything. You should be able to nail the focus in almost any situation.
Original version of article: http://digital-photography-school.com/9-tips-to-help-you-get-sharp-focus-at-night/
Modified by: Michael Bondanza